Abstract: In this study, the physicochemical properties of polysaccharides from Houttuynia cordata Thunb. fermented with Lactiplantibacillus plantarum HM6008 (FHCTP) were determined, and the antiallergic activity was evaluated using rat basophilic leukemia (RBL)-2H3 cells. The results showed that fermentation increased the ratio of mannose to sulfate in FHCTP. Compared with H. cordata Thunb. polysaccharides (HCTP), the particle size of FHCTP decreased by 26.67%, and its stability in aqueous solution increased. The inhibition rate of FHCTP on the degranulation of RBL-2H3 cells was significantly higher than that of HCTP, (82.79 ± 5.19)% versus (53.75 ± 1.95)%. After FHCTP intervention, the expression of fragment crystallizable epsilon receptor I (FcεRI) was significantly down-regulated, and the average fluorescence intensity decreased from 2 458.00 ± 7.50 to 1 495.00 ± 28.50. Both FHCTP and HCTP effectively inhibited the isomerization of cytoskeletal proteins and the increase of intracellular calcium ion concentration. In addition, in the mouse passive cutaneous anaphylaxis assay, FHCTP showed a more significant inhibitory effect on dye extravasation in mouse ears, indicating stronger antiallergic activity. In conclusion, FHCTP has better stabilizing effect on mast cells and effectively alleviates mast cell-mediated passive cutaneous anaphylaxis in mice. The results of this research are expected to promote the development and application of antiallergic products from edible and medicinal materials.

Key words: Houttuynia cordata; polysaccharides; probiotic fermentation; mast cells; anaphylaxis